Refrigeration



April 22, 1941. J H BEACH 2,239,141

REFRIGERATION Filed July 20, 1938 U 6 U U u 20 /6 J U /7 a f 7 1 r 36 Ll Em 'I IIIIIIlllIIIllllllllllllllllillllll iNVENTOR Jasfiee H; Beach ATTORNEY Patented Apr. 22, 1941 nsrmcuna'rron Justice H. Beach, Canton, Ohio, assignor to The Hoover Company, North Canton, Ohio, a corporation of Ohio Application July 20, 1938', Serial No. 220,204;

6 Claims. ((162-1195) 1 to exist between various parts'of the solution The present invention relates to the art of refrigeration and more particularly to a novel refrigerating system of the type utilizing a power I driven circulating element to circulate an inert pressure equalizing medium through certain portions of the system.

Previous three-fluid absorption refrigerating systems of the type utilizing arpower driven pressure equalizing medium circulator possessed certain disadvantages due to the fact that the high fan pressure impressed upon the evaporator was carried back through. various portions of the system including. the condenser and rectifier to the analyzer, thereby depressing the liquid level in the boiler-analyzer system. In order to utilize a system of this t the entire boiler analyzer structure is lowered to an extent which prohibitively increases the height of the system' which is sharply limited by the space limitations imposed by domestic refrigerating cabinets. Furthermore, such constructions introduce pressure fluctuations in the solution circuit which are carried through the weak solution line to the pump, thereby causing the pump to operate erratically or not at all. Additionally, the pressure produced by the pump is used up in-overcoming the resistance of various parts of the pressure equalizing medium circuit, and improper proportioning of the resistance of the various parts of the system frequently reflects in the solution circuit to an extent suflicient to prevent solution circulation and/or to cause the solution to block the absorber conduit.

As a result of these jvarious limitations upon previous systems, they are unable to utilize the circuit. The solution circuit is so connected into the other partsof the apparatus that it is not affected bytransient conditions produced within various parts of the refrigerating system, and the strong solution return cnduit,is subjected substantially to the same pressure at each end thereof wherebyit is not aflected by highly efficient and desirable non-submergedplate-type analyzer without greatly lowering the level of the boiler-analyzer and providing a pressure balancing liquid column in the strong solution circuit between the absorber and the analyzer. Previous systems are provided with a solution reservoir, but common practice has been to place the reservoir in such position that it functions simply as a reservoir and has no effect on the flow of fluids through the solution circuit except that which would naturally be produced by a relatively large quantity of solution contained in the solution reservoir.

Accordingly, it is the principal object of the present invention to provide a, three-fluid absorption refrigerating system of the type utilizing a power driven circulator for the pressure equalizing medium in which the solution flow is maintained substantially constant and in which relatively large pressure differentials are permitted the discharge pressure of the circulating-Ian.

It is a further object of this invention to provide an absorption refrigerating system of the type above described in which the generator or boiler-analyzer assembly and' the strong solution conduit are effectively shielded'from' the high pressure prevailing in the evaporator and from the discharge pressure of the circulating fan thereby permitting the relative position 01' the generator and absorber to be determined independently of the pressures developed by the fan.

.It is a further object of the invention to provide a solution circuit in an absorption refrigerating system of the type above described in which the solution reservoir is placed in the weak solution. circuit in such fashion that it effectively stabilizes the solution levels in the circuit and particularly on the circulating gas Jift pump to provide for steady, uniform and efii'cient operating conditions of the system as a whole.

It is a further object -of the invention to provide a refrigerating system of the type above described in which the condenser is connected into the evaporator through the intermediary of a pressure balancing liquid column which effectively .shields the condenser from the pressure prevailing in the evaporator, and additionally to vent the condenser "into a part of the circuit at which the pressure is the same as that prevailing at the inlet of thestrong solution return line from the absorber, thereby assuring that the same pressure shall exist throughout the strong solution and vapor circuits.

It is 'a further object of the invention to provide an absorption refrigerating system in which the generator or boiler-:analyzer assembly may extend substantially to .the level of the absorber.

It is a further object of the invention to provide a refrigerating system of the above described character in which the strong solution line ispositioned to absorb waste heat .from the system,

' thereby to increase the emciency thereof and to utilize the thermosyphonic action of the 'wastetion to render the operation of the solution circuit entirely independent of the relative distribution of the resistance in the gas circuit between the evaporator and the gas heat exchanger.

Other objects and advantages of the invention will become apparent as the description proceeds when taken in connection with the accompanying drawing, in which Figure 1 is a diagrammatic representation of a refrigerating system embodying the present invention with certain portions thereof drawn isometrically and on an enlarged scale.

Figure 2 is an enlarged scale isometric view of a modified form of the invention.

Referring now to the drawing in detail, and first to Figure 1 thereof, there is disclosed a threefiuid absorption refrigerating system comprising a generator including a boiler B and an analyzer D, and air-cooled rectifier R, a tubular air-cooled condenser C, an evaporator E, a gas heat exchanger H, a tubular air-cooled absorber A, a solution reservoir S, a liquid heat exchanger L, and a circulating fan F which is driven by an electrical motor M. The above described elements are interconnected by various conduits to form a plurality of gas and liquid circuits constituting a complete refrigerating system to which reference will be made in more detail hereinafter.

The refrigerating system will be charged with a suitable refrigerant, such as ammonia, a suitable absorbent, such as water, and a suitable inert pressure equalizing medium, such as nitrogen.

The generator may be heated in any suitable manner as by an electrical cartridge heater or by a gas burner as may be desired. The circulating motor M and the heater for the generator may be controlled in any suitable or desired manner. A preferred'control mechanism is disclosed in the co-pending application of Curtis C. Coons, Serial No. 148,424, filed June 16, 1937.

The application of heat to the generator liberates refrigerant vapor from the strong solution therein contained. The vapor so liberated passes upwardly through the analyzer D passing backwardly and forwardly across the staggered baflle plates l2 in counterflow relationshipto strong solution flowing downwardly through the analyzer. Further refrigerant vapor is generated in the analyzer by the heat of condensation of absorption solution vapor generated in boiler B.

The refrigerant vapor is conducted from the ipper portion of the analyzer D to the upper portion of the condenser C through a conduit l3 which includes the air-cooled rectifier R wherein 'any vapor of absorption solution passing through the analyzer is condensed and is returned to the analyzer through the conduit I3. The refrigerant vapor is liquified in the condenser by heat exchange relation with atmospheric air and is discharged from the bottom portion thereof through a conduit l5 into a downwardly extending conduit 16. The bottom portion of the conduit I6 connects to the bottom portion of an upwardly extending conduit I'| through a U-bend It. The conduit I6 is appreciably longer than the conduit I! for a purpose to be described hereinafter. The conduit I1 opens at its upper end into a conduit which discharges into the evaporator in a manner to be described more fully hereinafter.

The weak solution formed in the generator by the generation of refrigerant vapor therefrom is conveyed from the boiler through a conduit 22', the inner path of the liquid heat exchanger L, and a conduit 23 into the solution reservoir S.

The weak solution is conveyed from the solution reservoir S through a U-shaped conduit 24 which opens into the bight portion of a U-shaped twin gas lift pump 25 which discharges into an extension conduit 26 on the upper portion of the absorber A. It is apparent that the conduit 26 is materially above the solution level normally pre vailing in the boiler-analyzer reservoir system wherefore some means must be provided to elevate the absorption solution into the conduit 26. For this purpose a small bleed conduit 21 is connected to the discharge conduit 28 of the circulating fan F and branches into a pair of conduits 29 and 30 each of which opens into one of the legs of the twin gas lift pump 25 below the solution level normally prevailing in the reservoir whereby the weak solution is elevated into the absorber by v gas lift action.

The absorber A has been illustrated as extending vertically for pu poses of. convenience. The absorber may be in any planefrom the vertical to a plane slightly inclined to the horizontal which is the preferred arrangement because of the small vertical space occupied by an absorber in this position.

In the absorber the weak solution flows downwardly by gravity in counterflow to the rich .pressure equalizing medium refrigerant vapor mixture flowing upwardly therethrough in a manner to be described more fully hereinafter. The refrigerant vapor content of the mixture is absorbed in the absorption solution and the heat of absorption is rejected to the surrounding air by the air-cooling fins which are mounted on the exterior walls of the absorber vessel. The strong solution formed in the absorber collects in the bottom portion thereof and discharges into' a conduit 32 which opens into the'outer path of the liquid heat exchange L. From the outer path of the liquid heat exchanger L the strong solution is conveyed to the upper portion of the analyzer D by a strong solution return conduit 33 which is in heat exchange relationship with the top portion of the boiler B and with the side wall of the vertically extending analyzer D for a purpose to bedefined more fully hereinafter.

The lean pressure equalizing medium refrigerant vapor mixture formed in the absorber A is taken from the upper portion thereof through the conduit 354into the suction side of the circulating fan F in which it is placed under pressure and discharged through the conduit 28 into the outer path of the gas heat exchanger H. The pressure equalizing medium under pressure is conveyed from the outer path of the gas heat exchanger H through a downwardly extending conduit 36 into the bottom portion of the evaporator E.

The evaporator E illustrated herein is that form of evaporator illustrated and described in detail in the co-pending application of Curtis C. Coons and William H. Kitto, Serial No. 220,189, filed July 20, 1938. Briefly, the evaporator herein disclosed comprises three horizontally extending coil sections 31,38 and 39 and an upper enlarged finned box-cooling evaporator section 40. The conduit 36 opens into the coil section 31. The coil sections 31 and 38 are connected by a riser conduit II. The coil sections 38 and 39 are connected by a riser conduit 42, and the coil sections 39 of the box-cooling conduit 0 are connected by ariser conduit 43. The evaporator is constructed and arranged so that it is adapted to be enclosed in a suitable housing including shelves resting on the various coil sections upon which ice freezing trays 'mayconveniently be mounted. Other forms and arrangements of evaporators in which refrigerant liquid is propelled by an inert medium may however be used without departing from the spirit or the scope supplied to the evaporator enters the same 51- multaneously with the pressure equalizing me-. dium which is placed under pressure by the circulating fan F. The diameter of the conduits 30 forming the evaporator are relatively small wherefore the pressure equalizing medium flows through such evaporator conduits with a higher velocity than has been the previous practice in this art. The rapidly flowing pressure equalizing medium sweeps or drags the liquid refrigerant with it through the evaporator into the boxcooling conduit 40 as the refrigerantis evaporating to produce refrigeration. In the conduit 40 the velocity of the inert gas stream is relatively slower by reason of the large diameter of that conduit and the liquid refrigerant flows therethrough simply by gravity. A full explana-* tion of this phenomenon will be found in the above referred to applicationof Curtis C. Coons and William H. Kitto.

The rich pressure equalizing medium refrigerant vapor mixture formed in the evaporator is conducted therefrom into the inner path of the gas heat exchanger H through a conduit 45. The opposite end of the gas heat exchanger H communicates with the bottom portion of the absorber A through a conduit 46. In the absorber A the rich pressure equalizing medium and refrigerant vapor mixture flows upwardly in counterflow to absorption solution to absorb the refrigerant vapor content of the mixture in the manner heretofore described. I

The bottom coil 31 of the evaporator is provided with a drain conduit 48 which opens into the strong solution return conduit 32. The conduit 48 opens into the top half portion of the coil section 31 whereby it will not completely drain such conduit.

The upper portion of the discharge conduit l of the condenser is vented through a vent conduit 49 into the bottom portion of the absorber A adjacent its point of connection with the strong solution return conduit 32. i

The solution reservoir S is vented through a conduit 50 into the suction conduit 35 of the circulating fan.

The operation and advantages of this form of the invention will now be described: The-circulating fan F places the pressure equalizing medium discharged therefrom under a small pressure, for example, a pressure of approximately 4 of water. Though this pressure differential is small, it can cause serious difllculti'es in various parts of the system because it may necessitat'e the rearrangement of the levels of various relatively high pressure, namely, the high pressure conduit 36 which connects directly to the discharge conduit of the fan F through the gas heat exchanger H.

In order to prevent the relatively high pressure solution return conduit. v

The solution reservoir S is vented directly into v prevailing in the conduit 36 from being carried back through the condenser discharge conduit,

thecondenser, and conduit I 3 or to the generator, the conduit l6 has been made'appreciably longer than the conduit l1 wherefore a pressure balancing column of liquid, is formed in the conduit l6 which extends abovethe point of con-, nection between the conduits l1 and 20 adistance suflicient to balance the increased pressure in conduit 36 produced by the circulating fan F. As aresult of this construction, the pressure prevailing in the system comprising the generator, the conduit 13 and condenser C is lower than that prevailing in the conduit 36. The analyzer is also connected through the conduit 33, liquid heat exchanger L, and conduit 32 to the absorber, but it will be noted that its point of connection with the absorber is such that the pressure prevailing in the absorber at that point is approximately equal to the suction pressureof the gas circulating fan. Also the vent conduit '!9 from the condenser system opens into the ab-' sorber A at the same point at which the conduit 32 opens thereinto whereby substantially the same pressure prevails throughout the system including the condenser, generator, and strong the suction inlet of the circulating fan F by the conduit 50, wherefore the weak solution circuit as well as the generator is subjected to the suction pressure of the circulating fan. This possesses the additional advantage that the gas lift pump is enabled to operate with the maximum -possible pressure differential present in the sys- .absorber maybe arranged very compactly vertically because the present invention provides means preventing the pressure differential created in the gas circulator from affecting the liquid levels in the absorber and generator. The,

circulating fan operates at a constant speed and: is not materially affectediby changesin pressure conditions which sometimes occur in the evaporator-gas heat exchanger circuits; therefore, these pressure fluctuations are not reflected in v the absorption solution circuit and do not produce transient and undesirable conditions therein. Moreover, by placing the solution reservoir ..in the weak solution circuit the large ,area' of solution therein contained prevents the effective liquid level on the gas lift pump from fluctuating due to transient conditions sometimes occurring in the generator. I

It will be apparent that vent 49 also serves to purge the condenser-boiler assembly of inert gas which may escape thereinto from the inert gas circuit. Some inert gas is sought to be carried into theboiler along with the rich absorption solution and passes from there into the con,- denser. If means is not provided for conveying this inert gas back into the inert. gas circuit, sufllcient thereof will collect in the condenser to interfere with the condensation of refrigerant vapor, and finally the partial pressure of the inert gas in the condenser will become so high that substantially-no refrigerant vapor can be condensed. When this condition prevails, it is of course impossible to produce refrigeration. However, the present construction entirely avoids the possibility of such a condition ever existing because vent 49 will conduct the inert gas back to its proper habitat in the system. But it is to be noted that by the novel construction and arrangement of this vent with respect to the high and low pressure sides of the gas circulating means and with respect to the pressure balancing device, the purging function is accomplished without adversely afiecting the pressure balancing device or the other liquid levels in the system.

One of the most important advantages of the above described construction and arrangement is the fact that the entire generator, solution circult and condenser system is not affected by the pressure prevailing in the conduit 36; therefore, it is not necessaryto lower the analyzer-inlet to a level below the strong solution outlet of the absorber to provide for a liquid column in the conduit 32 above the level of the junction of the analyzer D and the conduit 33 of sufficient height to balance the pressure difference existing between the bottom portion of the absorber A and the evaporator inlet conduit 36; This permits the boiler-analyzer system to be raised several inches in height which is of extreme importance due to the rigidspace limitations imposed upon domestic refrigerating systems by the cabinets into which they must be placed, and it also permits the use of the efficient non-submerged baflie type analyzer illustrated, with resulting improvement in the efliciency of the system as a whole.

Referring now to Figure 2, there is disclosed a modified form of the invention. This form of the invention is designed and intended to be utilized with the system disclosed in Figure 1 and is identical therewith in every respect except in a few particulars to be noted hereinafter. portions of the construction of Figure 2 which are identical with the construction of Figure -1 are given the same reference characters primed.

In this form of the invention the rich mixture discharge conduit 45' of the evaporator and the lean mixture inlet conduit 36' of the evaporator are connected by a U-shaped conduit 60 which extends upwardly a slight distance into the conduit 45 in order that it may not drain the conduit 45' and opens into the conduit 36 after extending an appreciable distance threbelow. The condenser discharge conduit l now opens into the U-shaped conduit 60 at a level above the level of the intersection of the conduits 36 and 60. By reason of this construction the pressure prevailing in the conduit i5 is that prevailing in the discharge conduit 45' of the evaporator. The pressure difference between the conduits 36' and 45', which in this construction is substantially the major portion of the discharge pressu're of the'circulating fan F, is balanced by a liquid column in the leg of the conduit 60 opening into the conduit 45' which extends above the level of the junction of the conduits 60 and 36'. This construction replaces the conduit construction i6, i1 and vent 49 disclosed 'in' Figure 1.

In this form of the invention the pressure prevailing in the condenser, conduit l3 and the refrigerant generator. will be greater than that prevailing in the conduit 32by an amount equal Those to the pressure drop through the gas heat exchanger H. However, with some preferred constructions of gas heat exchanger the resistance to gas flow therethrough is very small, wherefore the construction in Figure 2 may be utilized without adversely affecting the solution circuit. The construction of Figure 2 is preferred where it is possible to use the same because it is sim-' pler and cheaper to manufacture than the construction illustrated in Figure 1.

As illustrated in Figure 2, the condenser could only extend to a level slightly above the level of the middle coil section 38', but this has been done merely for: the convenience of illustration, as the point of connection between the conduits 36 and 60 could be lowered to the level of the coil section 31' without interfering in any manner with the operation of the system. In this event the condenser should extend to a level only a few inches above the level of the lowest coil section 31.

The invention disclosed in the present application is particularly advantageous and eflicient because of the manner in which the solution circuit, condenser, and generator are shielded from the effects of the discharge pressure of the fan without affecting the operation of the absorber evaporator system and without permitting transient conditions in the absorber evaporator system to affect the flow within the solution circuit. Additionally, this arrangement provides a means whereby the level of the liquid on the gas lift pump can be maintained substantially constant which will permit the pump to operate under uniform conditions and at its maximum efiiciency. This is highly important for the reason that any fluctuation in the rate of discharge from the gas lift pump immediately produces undesirable action in the absorber. Such action may take the form of improper stripping of the inert gas in the case of too small a discharge from the circulating pump, or it may cause weak solution to discharge into the analyzer in the event of too rapid discharge from the gas lift pump. Obviously, either of these conditions will produce undesirable conditions throughout the circuit because the evaporator either will not be properly supplied with liquid refrigerant or it will be supplied with rich gas which will inhibit proper evaporation of the refrigerant.

While the invention has been illustrated and described herein in considerable detail, it is not to be limited to the constructional details illustrated and described. Various changes in construction, arrangement and proportion of the parts may be made without departing from the spirit of the invention or the scope of the appended claims.

I claim:

1. Refrigerating apparatus comprising a solution circuit including a boiler and an absorber, a pressure equalizing medium circuit including an evaporator and said absorber, means for producing flow of the pressure edualizing medium in said circuit, said pressure equalizing medium flow producing means being arranged to propel the pressure equalizing medium through said evap.-'

orator with a velocity sumcient to drag the refrigerant liquid through said evaporator, means for supplying refrigerant vapor generated in said boiler to said evaporator in liquid phase including a liquid pressure balancing meansjand means venting the boiler side of said pressure balancing means to a low pressure portion of the apparatus.

2. Absorption refrigerating appai atuscomprising a boiler, an absorber, an analyzer, means for conveying strong solution from said absorber to said analyzer, means for conveying weak solution from said boiler to said absorber, an even orator, means for supplying refrigerant vapor generated in said boiler to said evaporator in liquid phase, means for propelling a .pressure equalizing medium through a circuit including the evaporator and absorber with sufiicient velocity to propel liquid refrigerant upwardly through the evaporator, and means for maintaining the solution level in said boiler-analyzer below the strong solution inlet to the analyzer.

3. Absorption refrigerating apparatus comprising a boiler, an absorber, an analyzer, means for conveying strong solution from said absorber to said analyzer, means for conveying weak solution from said boiler to said absorber, an evaporator, means for supplying refrigerant vapor generated in said boiler to said evaporator in liquid phase, means for propelling a pressure equalizing medium through a circuit including the evaporator and absorber with suflicient velocity to propel liquid refrigerant from one point to another in the evaporator, means for maintaining the solution level in said boiler-analyzer below the strong solution inlet to the analyzer, a reservoir in said weak solution circuit, a gas lift pump for elevating weak solution from the reservoir into said absorber, and means for diverting a portion of the pressure equalizing medium discharged by said propelling means into said gas lift pump.

4. Absorption refrigerating apparatus comprising a boiler, an absorber, an analyzer, means for conveying strong solution from said absorber to said analyzer, means for conveying weak solution from said boiler to said absorber, an evaporator, means for supplying refrigerant vapor generated in said boiler to said evaporator in liquid phase, means for propelling a pressure equalizing medium through a circuit including the evaporator and absorber with sufficient velocity to sweep liquid refrigerant along the evaporator, means for maintaining the solution level in said boiler-analyzer below the strong solution inlet to the analyzer comprising means forming a pressure balancing liquid column between said analyzer and said evaporator, and means for venting the analyzer side of said column to a portion of the system containing pressure equalizing medium and strong solution.

5. Refrigerating apparatus comprising a solution circuit including a generator and an absorber, a pressure equalizing medium circuit including an evaporator and said absorber, means for producing flow of the pressure equalizing medium in said circuit, said pressure equalizing medium flow producing means being constructed and arranged to propel the pressure equaliz-. ing medium through said evaporator with sufficient velocity to sweep liquid refrigerant from a lower to a higher point in said evaporator, means for supplying liquid refrigerant produced from refrigerant vapor generated in said generator to said evaporator, said last mentioned means including a liquid pressure balancing means, and means connecting the generator side of said pressure balancing means to a low pressure portion of the apparatus.

6. Refrigerating apparatus as set forth in the preceding claim characterized by the fact that said evaporator includes a plurality of sections one of which is a box cooling section normally functioning at a higher temperature than another section and connected to receive liquid refrigerant from said last mentioned section by the sweeping action of the propelled pressure equalizing medium.

JUSTICE H. BEACH. 

